Many integrated circuits include field programmable gate array systems that incorporate an array of look up tables. A look up table transforms an input data into an output data that is different from the input data, where the output data is typically more desirable. The look up table(s) can simplify some computing applications, and this can save computing time. For example, look up tables have been used to calculate the trigonometric sine function. The look up table can pre-calculate several sine values, and the integrated circuit can then retrieve the closest sine value from the look up table instead of independently calculating it. In some embodiments, the integrated circuit may interpolate the sine value from two values retrieved from the look up table(s). This reduces the computation time because the sine value is essentially retrieved instead of being calculated.
Many look up tables can be written to, so the look up table can be converted from one function to another. In many embodiments, the look up table(s) have separate read and write circuits, where the read circuit is utilized to provide an input to the look up table and then retrieve the desired output. The write circuit is utilized when the look up table is converted from one function to another, such as from sine values to cosine values. Many other functions are also possible. The look up table includes a plurality of memory cells, and each memory cell is typically protected by a transistor within the write circuit to prevent unintended changes when other memory cells are written over. The large quantity of transistors requires space in the integrated circuit, and space is limited.
Accordingly, it is desirable to provide integrated circuits with look up tables that limit the amount of space required for operation of the look up tables, and methods of producing and operating the same. In addition, it is desirable to provide look up tables with memory cells, where reduced energy is required to write over the memory cells, and methods of producing and operating the same. Furthermore, other desirable features and characteristics of the present embodiments will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background.